Knowledge Panels are additional information that you see in some Google Search results.
This information is automatically generated from various sources.
This is an example of a Knowledge Panel for Apple (the panel on the right).

What is the Knowledge Panel used for?
You probably already use the knowledge panel when you search in Google.
This panel contains lots of additional information about a company, Apple in our example above.
This information is stored by Google and provides a richer search result.
How do I claim my Knowledge Panel?
The first step is to get verified by Google and then you can claim a Knowledge Panel.
How do I update my Google Knowledge Panel?
Google provide instructions on how to update your Knowledge Panel, where you provide suggestions for them to review.